1. Field of the Invention
The present invention relates to a display device. More specifically, the present invention relates to a liquid crystal display (LCD) device capable of reducing power consumption and a method of reducing power consumption of an LCD device.
2. Discussion of the Related Art
In general, portable LCD devices are commonly operated using batteries, and therefore, have a limited playing time. Accordingly, conserving battery power is especially important in order to provide the longest possible playing time of the LCD device for a given battery capacity. Alternatively, conservation of battery power allows for a smaller battery capacity of a given playing time of the LCD device.
LCD devices commonly make use of backlight units to provide light for viewing images on a display panel. However, as much as one-half of the power consumed by an LCD device is from use of the backlight unit. Accordingly, most LCD devices use various techniques to reduce power consumption of the backlight unit. For example, laptop computers may automatically reduce the output (i.e., brightness) of the backlight unit after a certain period of inactivity. Moreover, laptop computers, as well as LCD television displays, may reduce the brightness of the backlight unit in response to low ambient light levels at the viewing location of the laptop computer or LCD television display.
Although many different techniques have been developed to extend the playing time of the portable LCD devices, most techniques strive to reduce power consumption of the backlight unit. These techniques include simultaneously reducing the brightness of the backlight unit and modification of transfer characteristics of the video path in order to reduce or minimize degradation of images displayed on the display panel, such as perceived loss of image brightness and image contrast. An example of this technique is described by W-C. Cheng and M. Pedram in “Power Minimization in a Backlit TFT-LCD Display by Concurrent Brightness and Contrast Scaling,” Proc. of Design Automation and Test in Europe, February 2005, pp. 252-259.
However, these various techniques for extending the playing time of portable LCD devices fail to consider conserving more power as battery charge diminishes. Accordingly, an improved technique is required that dynamically conserves power of portable LCD devices.